Benefits

Immediate access to and direct understanding of the target language.
Accessible, achieveable, provable knowledge.
- Come back any time to prove it again.
Repeated testing beats passive review. When you guess and get it right, you show you know it -- not just "maybe I heard it once."
For older learners: Teachionary reduces the executive burdens of building and shuffling flashcards. Just show up and participate.
Supports language explorers: students, travellers, even new in-laws!